glusterfs: discard (hole punch) support

Add support for the DISCARD file operation. Discard punches a hole
in a file in the provided range. Block de-allocation is implemented
via fallocate() (as requested via fuse and passed on to the brick
fs) but a separate fop is created within gluster to emphasize the
fact that discard changes file data (the discarded region is
replaced with zeroes) and must invalidate caches where appropriate.

BUG: 963678
Change-Id: I34633a0bfff2187afeab4292a15f3cc9adf261af
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.org/5090
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 122 insertions, 0 deletions

diff --git a/xlators/protocol/server/src/server-rpc-fops.c b/xlators/protocol/server/src/server-rpc-fops.c
index 4b847eabd86..55e30fdd782 100644
--- a/xlators/protocol/server/src/server-rpc-fops.c
+++ b/xlators/protocol/server/src/server-rpc-fops.c
@@ -2008,6 +2008,45 @@ out:
         return 0;
 }
 
+int
+server_discard_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
+                   int32_t op_ret, int32_t op_errno,
+                   struct iatt *statpre, struct iatt *statpost, dict_t *xdata)
+{
+        gfs3_discard_rsp rsp	 = {0,};
+        server_state_t    *state = NULL;
+        rpcsvc_request_t  *req   = NULL;
+
+        req = frame->local;
+        state  = CALL_STATE (frame);
+
+        GF_PROTOCOL_DICT_SERIALIZE (this, xdata, (&rsp.xdata.xdata_val),
+                                    rsp.xdata.xdata_len, op_errno, out);
+
+        if (op_ret) {
+                gf_log (this->name, GF_LOG_INFO,
+                        "%"PRId64": DISCARD %"PRId64" (%s) ==> (%s)",
+                        frame->root->unique, state->resolve.fd_no,
+                        uuid_utoa (state->resolve.gfid),
+                        strerror (op_errno));
+                goto out;
+        }
+
+        gf_stat_from_iatt (&rsp.statpre, statpre);
+        gf_stat_from_iatt (&rsp.statpost, statpost);
+
+out:
+        rsp.op_ret    = op_ret;
+        rsp.op_errno  = gf_errno_to_error (op_errno);
+
+        server_submit_reply(frame, req, &rsp, NULL, 0, NULL,
+                            (xdrproc_t) xdr_gfs3_discard_rsp);
+
+        GF_FREE (rsp.xdata.xdata_val);
+
+        return 0;
+}
+
 /* Resume function section */
 
 int
@@ -2975,6 +3014,26 @@ err:
         return 0;
 }
 
+int
+server_discard_resume (call_frame_t *frame, xlator_t *bound_xl)
+{
+        server_state_t *state = NULL;
+
+        state = CALL_STATE (frame);
+
+        if (state->resolve.op_ret != 0)
+                goto err;
+
+        STACK_WIND (frame, server_discard_cbk,
+                    bound_xl, bound_xl->fops->discard,
+                    state->fd, state->offset, state->size, state->xdata);
+        return 0;
+err:
+        server_discard_cbk(frame, NULL, frame->this, state->resolve.op_ret,
+			   state->resolve.op_errno, NULL, NULL, NULL);
+
+        return 0;
+}
 
 
 /* Fop section */
@@ -3213,6 +3272,68 @@ out:
 
         return ret;
 }
+
+
+int
+server3_3_discard(rpcsvc_request_t *req)
+{
+        server_state_t    *state = NULL;
+        call_frame_t      *frame = NULL;
+        gfs3_discard_req args	 = {{0},};
+        int                ret   = -1;
+        int                op_errno = 0;
+
+        if (!req)
+                return ret;
+
+        ret = xdr_to_generic (req->msg[0], &args,
+                              (xdrproc_t)xdr_gfs3_discard_req);
+        if (ret < 0) {
+                //failed to decode msg;
+                req->rpc_err = GARBAGE_ARGS;
+                goto out;
+        }
+
+        frame = get_frame_from_request (req);
+        if (!frame) {
+                // something wrong, mostly insufficient memory
+                req->rpc_err = GARBAGE_ARGS; /* TODO */
+                goto out;
+        }
+        frame->root->op = GF_FOP_DISCARD;
+
+        state = CALL_STATE (frame);
+        if (!state->conn->bound_xl) {
+                /* auth failure, request on subvolume without setvolume */
+                req->rpc_err = GARBAGE_ARGS;
+                goto out;
+        }
+
+        state->resolve.type   = RESOLVE_MUST;
+        state->resolve.fd_no  = args.fd;
+
+	state->offset = args.offset;
+	state->size = args.size;
+	memcpy(state->resolve.gfid, args.gfid, 16);
+
+        GF_PROTOCOL_DICT_UNSERIALIZE (state->conn->bound_xl, state->xdata,
+                                      (args.xdata.xdata_val),
+                                      (args.xdata.xdata_len), ret,
+                                      op_errno, out);
+
+        ret = 0;
+        resolve_and_resume (frame, server_discard_resume);
+
+out:
+        free (args.xdata.xdata_val);
+
+        if (op_errno)
+                req->rpc_err = GARBAGE_ARGS;
+
+        return ret;
+}
+
+
 int
 server3_3_readlink (rpcsvc_request_t *req)
 {
@@ -5867,6 +5988,7 @@ rpcsvc_actor_t glusterfs3_3_fop_actors[] = {
         [GFS3_OP_FSETATTR]    = { "FSETATTR",   GFS3_OP_FSETATTR, server3_3_fsetattr, NULL, 0},
         [GFS3_OP_READDIRP]    = { "READDIRP",   GFS3_OP_READDIRP, server3_3_readdirp, NULL, 0},
 	[GFS3_OP_FALLOCATE]    = { "FALLOCATE",	GFS3_OP_FALLOCATE, server3_3_fallocate, NULL, 0},
+	[GFS3_OP_DISCARD]     = { "DISCARD",	GFS3_OP_DISCARD, server3_3_discard, NULL, 0},
         [GFS3_OP_RELEASE]     = { "RELEASE",    GFS3_OP_RELEASE, server3_3_release, NULL, 0},
         [GFS3_OP_RELEASEDIR]  = { "RELEASEDIR", GFS3_OP_RELEASEDIR, server3_3_releasedir, NULL, 0},
         [GFS3_OP_FREMOVEXATTR] = { "FREMOVEXATTR", GFS3_OP_FREMOVEXATTR, server3_3_fremovexattr, NULL, 0},